Method of constructing roadways.



1). B. W. ALEXANDER. METHOD OF GONSTRUOTING ROADWAYS.

APPLICATION FILED APR.9, 1912. V

Patented Dec. 30, 1913 wzlfineaSea Q mu/ NITED STATES PATENT OFFICE.

DANIEL AsII. w. ALEXANDER, or nos ANGELES, CALIFORNIA.

the body portion is made up of rock suitably the same.

treated for preventing its shifting, suitable filling means being provided in connection therewith, after which a wearing surface forming a smooth roadway is applied above It is a further object of the invention to construct a roadway by preparing grouting mate-rial with an adhesive coating, of material tending to prevent the shifting of the individual pieces and filling the space in said grouting with fine material of any sort, after which the bed thus formed is treated with" oil, and a surfacing material placed above the same and further treated with oil. In the accompanying part ofthis sectional view of a road bed constructed in accordance with the present method. Fig. 2 is a fragmentary edge portion of the roadway upon an enlarged scale. Fig. 3 is an enlarged sectional view through a group 'of the bed stones of the roadbed showing the coating applied thereto. i

The details and features of the invention will now be more particularly described, reference being had to the said drawing in which 5' indicates the grouting or base rock of the roadbed formed in accordance with this method, 6 the finer filling placed with the rock, and 7 a layer of oil above the same,

and 8 and 9 a surfacing material coat of oil respectively. in forming road beds heretofore where large crushed rock is used as the base strataor layer, and particularly in oiled roads, the large rock at the base of the composition is found to readily shift in use so as to permit the oiled surface above to sink at intervals and form ruts after being used awhile.

One of the important features of the present invention is to provide a basic portion of the roadbed with crushed rock which is treated with a .suitable coating of material and surface METHOD OF CONSTRUCTING Specification of Letters Patent. Application filed April 9,

mg at Los Angeles, in the county of Los Andrawing forming aspec1ficat1o-n, Figure 1 1s a cross sectional view showing the.

ROADWAYS.

Patented Decca-i913. 1912. Serial No. 689,452. 1

slipping and shifting in the road bed, and also to preserve the rock from disintegration.

It is preferable to treat the crushed rock with bituminous substance. forming a bituminous coating as 10, clearly shown in Fig.

coating is 3. This bituminous substance or applied to the crushed rock before it is spread upon the roadbed, the substance or coating being allowed to harden or dry upon the rock before placing it upon the road bed. The ground is prepared in the usual way to form a roadbed being leveled to a proper with the coating as above described is spread over the ground to a suitable depth. The interstices of the rock are then filled with a finely crushed material, as for instance crushed rock that will pass through a number four mesh screen said filling being indicatedat 6 in the drawing. This material and the crushed rock are well a smooth compact base strata for the roadbed. i a

In actual practice the rock employed at the bottom of the roadbed is dipped or otherwise coated in bituminous material of a low penetration, from 300 F. to 500 F. according to the size of the rock, permitting the materials to cool While in motion or cooling them in water. This coated rock is then used in different proportions instead of the rock ordinarily used in making an oiled roadway. The rock ordinarily used is uncoated and is found to disintegrate through the action of moisture penetrating the roadbed so that it is more liable to shift from position and produce anuneven roadbed than if it was preserved in its original hardness. The rock thus prepared will, when combined in proper proportions to give the most desirable amount or volume of spaces or voids, which are then filled with clean screenings which are thrown on top of the rolled rock bed and carefully swept in. The roadway is next oiled with a suitable road oil, or oil just light enough to penetrate between the interstices of the coated rock and screenings. This oil is preferably heated to about 2 0 F. and will sink slowly into, and tend to soften the bituminous coating of the rocks so that [he cementing action is increased and the rock and screenings closely bound together to prevent shifting in the roadbed. Sand, as shown and designated as 8 in diadepth after which the crushed ro'ck treated rolled to form say at a temperature of adapted to prevent the pieces of rock from the rock, to a point where it will better ceother alternative form may be used which upkeep, and not raveled by the suction of automobile tires or shoved out of place by any passing trafiic. In other words a bituminous maoad'am roadway is produced with all its advantages, and a roadway made which more than saves in tenance what may be added by the cost of the bitumen used.

What I claim is: v

1. The 'method of producing roadways, comprising the coating of crushed rock of graded sizes with a hard bituminous material and then cooling the same, then applying the rock to the surface to be covered by a roadbed, then partially filling the voids with rock screenings, then applying heated oil to the mass and allowing it to penetrate therein to soften the hard and brittle bituminous coating of the rock so that a cementing action is obtained, then sanding and rolling the sand into the mass, and finally oiling the surface.

2. The method of constructing bitumigram, is then swept on top of the surface, and is thoroughly rolled in; and'then another application of oil, designated 9 in'the diagram, is applied upon the whole to complete the surface.

Instead of laying the materials for the roadbed as heretofore described, I may take the bitumen-coated graded rock and thor oughly mix the same with screenings and sand in proper proportions to fill the voids, after which the entire mass ma betransported to the place where it is to e laid, and rolled in place to form the roadbed. This rolled surface is finally treated with oil. This oil will penetrate and'soften the hard bitumen, or, as it is termed, will raise the penetration (consistency) of the bitumen, and assist in binding the. mass together, forming substantially the same character of roadbed as in the preferred form. Also anconsists in combining with the uncoated rock, rock screenings and sand incorporating therein the requisite amount of'powdered bitumen, all of these materials being in an unheated condition.- After thoroughly commingling or mixing the mass together it is transported to the place of use and rolled inplace upon the roadbed, after which the heated hydrocarbon is applied to bind the mass together, raising the penetration and forming a roadbed of substantially the same characteristics as heretofore described.

A roadway thus constructed produces a roadbed in which the oil will penetrate the mass and combine with the hard bitumen and thus raising the penetration to any desired point, depending on the amount of oil used and its specific gravity. Conversely it is found that the gravity of the oil is lowered by the solution of the bitumen from coating of graded rock with a hard bituminous material, then laying and rolling the crushed rock with form the basis of a roadbed, then oiling the roadbed and permitting the oil to penetrate tothe bituminous coverings of the rock and combining with said bitumen for the purpose of cementing bedtogether,- and then applying sand, and further oiling the roadbed to produce a smooth waterproof surface. 4

3. The method .of constructing roadways, comprisingthe mixing of hard bitumen, graded rock, rock screenings and sand, then spreading the mixture upon the rpad bed and rolling the same, and finally spraying sufficient oil to the rolled'mass to soften the hard bitumen and cement the rock, sand and screenings together to one homogeneous mass. I

In witness that I' claim the foregoing I have hereunto subscribed my name this 4th day of April, 1912.

D. BAsILW. ALEXANDER,

Witnesses:

EDMUND A. STRAUsE,

EARLE R. POLLARD.

ment the screenings and sand in the voids. Traffic will improve the road and the heat of the sun will tend to draw the bitumen t0 the wearing surface of the screenings and sand which .are otherwise primarily deficient therein.

A road bed constructed in accordance. with this invention thus provides good roads for country and highway-uses which are smooth, dustless, cheap in initial cost and the item of main nous macadam roadways, comprising the rock screenings added to the particles of the roadthe interstices of 

